Spring Actuator

What is an actuator?

It is app monitoring tool for health check applications user some endpoint urls.

Monitoring our app, gathering metrics, understanding traffic or the state of our database
becomes trivial with this dependency.

The main benefit of this library is that we can get production grade tools without having to actually implement these features ourselves.

Actuator is mainly used to expose operational information about the running application –
health, metrics, info, dump, env, etc. It uses HTTP endpoints or JMX beans to enable us to
interact with it.

Once this dependency is on the classpath several endpoints are available for us out of the box.
As with most Spring modules, we can easily configure or extend it in many ways.

Problem

How can I monitor and manage my application?
How can I check the application's health?
How can I access application metrics?

Solution: Spring Boot Actuator

Exposes endpoints to monitor and manage your application
You easily get DevOps functionality out-of-the-box
Simply add the dependency to your POM file
REST endpoints are automatically added to your application

Spring Boot Actuator

Adding the dependency to your POM file

Endpoints are prefixed with: /actuator

ID	Description
auditevents	Exposes audit events information for the current application. Requires an AuditEventRepository bean.
beans	Displays a complete list of all the Spring beans in your application.
caches	Exposes available caches.
conditions	Shows the conditions that were evaluated on configuration and auto-configuration classes and the reasons why they did or did not match.
configprops	Displays a collated list of all @ConfigurationProperties.
env	Exposes properties from Spring’s ConfigurableEnvironment.
flyway	Shows any Flyway database migrations that have been applied. Requires one or more Flyway beans.
health	Shows application health information.
httptrace	Displays HTTP trace information (by default, the last 100 HTTP request-response exchanges). Requires an HttpTraceRepository bean.
info	Displays arbitrary application info.
integrationgraph	Shows the Spring Integration graph. Requires a dependency on spring-integration-core.
loggers	Shows and modifies the configuration of loggers in the application.
liquibase	Shows any Liquibase database migrations that have been applied. Requires one or more Liquibase beans.
metrics	Shows ‘metrics’ information for the current application.
mappings	Displays a collated list of all @RequestMapping paths.
scheduledtasks	Displays the scheduled tasks in your application.
sessions	Allows retrieval and deletion of user sessions from a Spring Session-backed session store. Requires a Servlet-based web application using Spring Session.
shutdown	Lets the application be gracefully shutdown. Disabled by default.
threaddump	Performs a thread dump.

If your application is a web application (Spring MVC, Spring WebFlux, or Jersey), you can use
the following additional endpoints:

ID	Description
heapdump	Returns an hprof heap dump file.
jolokia	Exposes JMX beans over HTTP (when Jolokia is on the classpath, not available for WebFlux). Requires a dependency on jolokia-core.
logfile	Returns the contents of the logfile (if logging.file.name or logging.file.path properties have been set). Supports the use of the HTTP Range header to retrieve part of the log file’s content.
prometheus	Exposes metrics in a format that can be scraped by a Prometheus server. Requires a dependency on micrometer-registry-prometheus.